forked from loafle/openapi-generator-original
`unicode` does not exist in py3, therefore since six is already imported switch to using `six.u` so that `unicode` is used on py2 and `str` is used on py3.
`unicode` does not exist in py3, therefore since six is already imported switch to using `six.u` so that `unicode` is used on py2 and `str` is used on py3.